This invention relates to intra-aortic balloon pump apparatus and more particularly to improved percutaneous intra-aortic balloon pumping apparatus.
Conventional intra-aortic balloon pumps are shown and described, for example, in U.S. Pat. Nos. 3,692,018, 3,504,662 and 3,939,820.
With increasing experience, the original indications for intra-aortic balloon pumping in cardiogenic shock due to acute infraction, post-operative severe low cardiac output state, or inability to wean from cardiopulmonary bypass have been extended to include refractory unstable angina in the period before and after infarction, recurrent life-threatening tachyarrhythmias, and preoperative support in the presence of severe left ventricular dysfunction. Recently, intra-aortic balloon pumping has been used both experimentally and clinically to reduce infarct size.
During the first few years following the introduction of the intra-aortic balloon pump for clinical use in 1968, balloon catheters were the subject of considerable development of design efforts. In the 1970's, most of the efforts in the field of intra-aortic balloon pumping were directed mainly toward clarifying the indications for and to reporting large clinical experiences with this therapeutic modality. During this period, no major advances in balloon technology were made. However, attention is again being focused on improving the design of balloon pump catheters. A major disadvantage of the design features of conventional intra-aortic balloon pumps is that they must be inserted by a surgical cutdown of the common femoral artery. Obviously, this results in considerable delay in the application of intra-aortic balloon pumping in situations in which it is indicated.
The only presently known available percutaneous intra-aortic balloon catheter comprises a single chamber balloon sealably disposed at the end of a catheter. The extreme end of the balloon is internally bonded to a stiff wire disposed within the balloon and which terminates at a swivel located at the junction of the catheter and the balloon. The balloon is wrapped around the wire by grasping the catheter and twisting the remote end of the balloon until the desired degree of wrapping is obtained. After the balloon is wrapped, the application of a vacuum to the interior of the balloon is relied on to maintain the balloon in its wrapped condition. Rotation during insertion is advised to tighten any loosening of the balloon wrapping. Neither during nor after insertion is access to the interior of the aorta available and no positive means are provided or possible to insure that the balloon remains fully wrapped during insertion or for effecting unwrapping of the balloon after insertion to insure that the balloon is fully unwrapped before pumping commences. Application of pressure to the interior of the balloon, together with manual rotation of the catheter, is relied on to effect unwrapping of the balloon and permit pumping to begin, and rewrapping of the balloon for removal is neither possible nor recommended. Failures with this type of balloon pump have been encountered in unwrapping of the balloon and in passage of the catheter through the aorta.